CN112916709B

CN112916709B - Helicopter blade edge-covering forming method

Info

Publication number: CN112916709B
Application number: CN202110024330.4A
Authority: CN
Inventors: 牛涛; 张艳苓; 陈福龙; 王耀奇
Original assignee: AVIC Beijing Aeronautical Manufacturing Technology Research Institute
Current assignee: AVIC Beijing Aeronautical Manufacturing Technology Research Institute
Priority date: 2021-01-08
Filing date: 2021-01-08
Publication date: 2023-04-28
Anticipated expiration: 2041-01-08
Also published as: CN112916709A

Abstract

The invention belongs to the field of titanium alloy sheet forming, and particularly relates to a helicopter blade edging forming method. The edge covering forming method comprises the following steps: performing preforming treatment on the thin-wall titanium alloy pipe to generate a flat special pipe; performing air pressure thermal expansion forming treatment on the flat special-shaped tube through an air expansion die to generate a double-edge-covered composite part; and cutting the double-edge-covered composite part to obtain the edge-covered part. The edge-covering forming method provided by the invention is suitable for large-size edge-covering forming treatment of the helicopter blade, and solves the problems that in the prior art, the requirement on the helicopter blade edge-covering forming processing equipment is high, or deformation and low precision are easy to occur by adopting sectional welding.

Description

Helicopter blade edge-covering forming method

Technical Field

The invention belongs to the field of titanium alloy sheet forming, and particularly relates to a helicopter blade edging forming method.

Background

The blade is an important component of a helicopter rotor system, and the helicopter rotor blade mainly comprises a composite material body, a deicing heating assembly and a front edge wrapping. Wherein leading edge bordures and is the important protective structure of paddle, its main roles include: the blade is protected from being washed by air when rotating at high speed, and the layering of the blade is prevented from being damaged; the composite material body of the blade and the ice heating component are protected from being impacted by raised sand dust, broken stone and other foreign matters, so that the integral air scouring resistance and foreign matter impact resistance of the composite material blade are improved.

At present, stainless steel or titanium alloy is generally adopted for the leading edge wrapping of the helicopter blade, the stainless steel is generally formed by cold stamping, and the titanium alloy is required to be formed by hot forming. The thermoforming process can achieve overall near net shape formation of the titanium alloy complex thin-walled component. However, the size of the platform of the current heated forming equipment is limited, the maximum size of the titanium alloy hot forming component is not more than 3 meters, the length of the rotor blade of the helicopter is at least more than 5 meters, and the edge of the rotor blade of the heavy helicopter is as long as 10 meters, so that the whole blade edge is difficult to directly form by the existing equipment.

The current method for edging helicopter rotor blades comprises the following steps: one is to use sectional forming and then splice by welding; however, the thickness of the wrapping edges is very thin, so that the wrapping edges are easy to deform, the precision is difficult to ensure, and the usability is affected. The other is a progressive forming method, but the method can only form simple parts with unchanged cross section shape, for example, the technical scheme disclosed in the patent number 201811561155.7 cannot be applied to the edge wrapping forming treatment of complex-shape parts with changeable cross section shape.

Disclosure of Invention

In view of the above problems, the present invention provides a helicopter blade edging forming method, comprising:

performing preforming treatment on the thin-wall titanium alloy pipe to generate a flat special pipe;

performing air pressure thermal expansion forming treatment on the flat special-shaped tube through an air expansion die to generate a double-edge-covered composite part;

and cutting the double-edge-covered composite part to obtain the edge-covered part.

Further, the wall thickness of the thin-wall titanium alloy pipe is 0.1 mm-3 mm.

Further, the pre-forming process includes a hot-roll forming process or a hot-extrusion forming process.

Further, the hemming forming method further includes:

cutting and adjusting the length of the flat foreign tube according to the predicted length of the edge-wrapping part and the length of the air-expanding die;

sealing plates are welded at openings at two ends of the flat special-shaped tube respectively, so that a closed cavity is formed inside the flat special-shaped tube;

a group of sealing plates are provided with first through holes, a gas expansion pipeline is welded at the position of each first through hole, and the gas expansion pipeline is communicated with the cavity inside the flat special-shaped pipe through the first through holes to obtain a pipe blank;

and installing the tube blank in an inflation die, and performing pneumatic thermal inflation forming treatment on the tube blank through the inflation die.

Further, the gas pressure thermal expansion forming treatment comprises:

placing one or more groups of the air-expanding molds provided with the tube blanks into a heating furnace, and heating to 700-1000 ℃ at a heating speed of 10-1000 ℃/h;

introducing inert gases such as argon and the like into the cavity of the tube blank through the inflation pipeline, wherein the pressurizing speed is 0.001-10 MPa/min, and the pressure maintaining time is more than 1s after the air pressure in the cavity of the tube blank is pressurized to 0.1-5 MPa;

and then cooling to below 600 ℃, opening the air-expanding die, and taking out the formed double-edge-covered composite part.

Further, the inflatable mold comprises a left mold, a right mold, a front stop block and a rear stop block; the opposite sides of the left die and the right die are respectively provided with a die groove, and the die groove structure corresponds to the edge-covering part structure; the front stop block and the rear stop block are identical in structure and are symmetrically arranged; the front stop block is provided with a second through hole.

Further, the installing the tube blank in the inflation die includes:

placing the tube blank in the grooves of the left die and the right die, wherein the front stop block is arranged at one end of the tube blank, which is provided with an inflatable pipeline, and the inflatable pipeline penetrates through the second through hole; the rear stop block is arranged at the other end of the tube blank; the left die, the right die, the front stop block and the rear stop block are fixedly connected through bolts.

Further, the cutting of the double-covered composite part includes: and cutting the double-edge-covered composite part in a laser cutting mode according to the shape digital-analog of the edge-covered part.

The edge-covering forming method provided by the invention is suitable for large-size edge-covering forming treatment of the helicopter blade, and solves the problems that in the prior art, the requirement on the helicopter blade edge-covering forming processing equipment is high, or deformation and low precision are easy to occur by adopting sectional welding.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 illustrates a flow chart of a helicopter blade taping forming method in accordance with an embodiment of the present invention;

FIG. 2 shows an exploded view of an inflatable mold with a tube blank installed in accordance with an embodiment of the invention;

FIG. 3 shows a schematic structural view of an edge covering component according to an embodiment of the invention;

FIG. 4 shows a schematic radial cross-section of a flat profile tube according to an embodiment of the invention;

fig. 5 shows a schematic view of a scenario when four inflatable molds are heated simultaneously according to an embodiment of the invention.

FIG. 6 is a schematic view of the process

In the figure: 1. a left die; 2. a right die; 3. a front stop block; 4. a rear stopper; 5. an inflatable pipeline; 6. a tube blank.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The embodiment of the invention provides a helicopter blade edging forming method, which is exemplified as shown in fig. 1 and 6, and comprises the following steps:

The helicopter blade edging forming method provided by the invention solves the problems that the requirements on edging forming processing equipment are higher or the deformation and the precision are lower easily caused by adopting sectional welding in the prior art.

Specifically, the wall thickness of the thin-wall titanium alloy pipe is between 0.1mm and 3.0mm, and the diameter specification of the thin-wall titanium alloy pipe is calculated and selected according to the edge-covering size.

The pre-forming process includes, but is not limited to, a hot roll forming process or a hot extrusion forming process. The thin-wall titanium alloy pipe is processed into a flat special-shaped pipe through pre-forming treatment, and the section shape of the flat special-shaped pipe is designed according to the edge-covering size, so that the flattened flat special-shaped pipe can be placed in an air inflation die.

Before the flat special-shaped tube is put into the inflation die, the length of the flat special-shaped tube needs to be cut and adjusted according to the length of the bag Bian Heqi inflation die; sealing plates are welded at openings at two ends of the flat special-shaped tube respectively, so that a closed cavity is formed inside the flat special-shaped tube. Specifically, the shape of the sealing plate is the same as the radial cross section shape of the flat special-shaped tube, and the sealing plate can be, but is not limited to, titanium alloy plates.

A first through hole is formed in one group of sealing plates, an air inflation pipeline is welded at the position of the first through hole, the air inflation pipeline can be a titanium alloy pipeline but is not limited to the titanium alloy pipeline, and the air inflation pipeline is communicated with the cavity inside the flat special-shaped pipe through the first through hole; obtaining a tube blank.

The inflatable mould comprises a left mould 1, a right mould 2, a front stop block 3 and a rear stop block 4, wherein the left mould 1 and the right mould 2 are identical in structure and symmetrically arranged as shown in fig. 2, mould grooves are formed in the opposite sides of the left mould 1 and the right mould 2, and the mould groove structures correspond to the edge-covering part structures; the front stop block 3 and the rear stop block 4 are identical in structure and are symmetrically arranged; the front stop block 3 is provided with a second through hole. When the pipe blank 6 is subjected to pneumatic thermal expansion forming treatment, the pipe blank 6 is placed in the die grooves of the left die 1 and the right die 2, the front stop block 3 is arranged at one end of the pipe blank 6, which is provided with the air expansion pipeline 5, and the air expansion pipeline 5 penetrates through the second through hole; the rear stop block 4 is arranged at the other end of the tube blank 6; the left die 1, the right die 2, the front stopper 3 and the rear stopper 4 are fixedly connected by, but not limited to, bolts. After the tube blank 6 is installed in the inflation mold, the pneumatic thermal inflation forming process is performed.

The pneumatic thermal expansion forming treatment comprises the following steps: placing the air-expanding die provided with the tube blank into a heating furnace; heating to 700-1000 ℃ and heating up at a speed of 10-1000 ℃/h; and introducing inert gases such as argon into the cavity of the tube blank through the inflation pipeline, wherein the pressurizing speed is 0.001-10 MPa/min, and maintaining the pressure for more than 1s after the air pressure in the cavity of the tube blank is pressurized to 0.1-5 MPa. And then cooling to below 600 ℃, opening the air-expanding die, and taking out the formed double-edge-covered composite part.

In the process of performing the pneumatic thermal expansion forming, a plurality of sets of inflation dies with tube blanks can be simultaneously placed into a heating furnace for inflation treatment at a time, and a plurality of double-edge-covered composite parts can be formed in one furnace.

Cutting the double-clad composite part comprises: and cutting the double-covered composite part by adopting a laser cutting mode according to the shape digital-analog of the covered part to obtain two covered parts.

According to the helicopter blade edging forming method provided by the embodiment of the invention, a thin-wall titanium alloy pipe is used as a raw material, the thin-wall titanium alloy pipe is processed into a flat special pipe through hot rolling or hot extrusion and the like, then the flat special pipe is processed into a double-edging composite part through an air pressure thermal expansion forming mode, and after one double-edging composite part is cut, two edging parts can be obtained. The invention solves the problems that the integral hot forming treatment of the edge-covered part has higher requirements on equipment, or the deformation is easy to occur by adopting sectional welding, the precision is lower, and the like.

Example 1

The finished part is expected to have a wall thickness of 0.5mm and a length of 5m, and a schematic outline of the part is shown in fig. 3. TC4 titanium alloy tube with outer diameter of 190mm and wall thickness of 0.6mm is adopted as raw material. The TC4 titanium alloy pipe is processed into a flat special-shaped pipe by adopting a hot rolling method, and the cross section shape of the flat special-shaped pipe is shown in figure 4. Processing the flat special-shaped tube into a length of 5.5m by a linear cutting method; and (3) welding TC4 titanium alloy plates with the same cross-sectional shape as the flat special-shaped tube on the two end surfaces of the flat special-shaped tube by adopting argon arc welding, wherein the thickness of each TC4 titanium alloy plate is 1mm, a hole with the diameter of 8mm is processed in the middle position of one TC4 titanium alloy plate, a titanium alloy inflation pipeline with the diameter of 8mm and the wall thickness of 1mm is welded in the position of the hole, and the titanium alloy inflation pipeline is communicated with the inner cavity of the flat special-shaped tube. The flat special pipe after the treatment is the pipe blank. Placing the tube blank into an air-expanding die, then placing the air-expanding die into a heating furnace, and heating to 910 ℃ at a heating speed of 100 ℃/h; then argon is introduced into the inner cavity of the tube blank through a titanium alloy inflation pipeline, and the tube blank starts inflation; the pressurizing speed is 0.02 MPa/min, the pressure in the tube blank is 1.5 MPa, and the pressure is maintained for 1h; and then cooling to room temperature, opening the air expansion mould, and taking out the double-covered composite part. And cutting the double-edge-covered composite part into two edge-covered parts according to an edge-covered digital die by adopting a laser cutting method.

Example 2

The finished part is expected to have a wall thickness of 0.8mm and a length of 10m, and a schematic view of the profile of the part is shown in FIG. 3. TC4 titanium alloy tube with external diameter of 240mm and wall thickness of 1.0mm is adopted as raw material. The TC4 titanium alloy pipe is processed into a flat special-shaped pipe by adopting a hot rolling method, and the cross section shape of the flat special-shaped pipe is shown in figure 4. Cutting the flat special-shaped tube into a length of 10.5m by a wire; and (3) welding TC4 titanium alloy plates with the same cross-sectional shape as the flat special-shaped tube on the two end surfaces of the flat special-shaped tube by adopting argon arc welding, wherein the thickness of each TC4 titanium alloy plate is 1mm, a hole with the diameter of 8mm is processed in the middle position of one TC4 titanium alloy plate, a titanium alloy inflation pipeline with the diameter of 8mm and the wall thickness of 1mm is welded in the position of the hole, and the titanium alloy inflation pipeline is communicated with the inner cavity of the flat special-shaped tube. The flat special pipe after the treatment is the pipe blank. Placing the tube blank into a die, and simultaneously placing four sets of dies and the tube blank into a heating furnace together, as shown in fig. 5; heating to 910 ℃ at a heating speed of 80 ℃/h; argon is simultaneously introduced into the four tube blanks through a titanium alloy inflation pipeline, the four tube blanks start to be inflated, the pressurizing speed is 0.02 MPa/min, the pressure in the tube blanks is 1.5 MPa, and the pressure is maintained for 1h; and then cooling to room temperature, opening the air expansion mould, and taking out the double-covered composite part. And cutting the double-edge-covered composite part into eight edge-covered parts according to the edge-covered digital die by adopting a laser cutting method.

Although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A helicopter blade edging method, the edging method comprising:

carrying out pre-forming treatment on the thin-wall titanium alloy pipe to generate a flat special pipe, wherein the pre-forming treatment comprises hot rolling forming treatment or hot extrusion forming treatment;

cutting and adjusting the length of the flat special-shaped tube according to the expected length of the edge-covering part and the length of the air-expanding die;

the pipe blank is arranged in an air expansion die, and the air pressure thermal expansion forming treatment is carried out on the flat special pipe through the air expansion die, so that a double-edge-covered composite part is generated;

the pneumatic thermal expansion forming treatment comprises the following steps:

argon inert gas is introduced into the cavity of the tube blank through the inflation pipeline, the pressurizing speed is 0.001-10 MPa/min, and the pressure maintaining time is more than 1s after the air pressure in the cavity of the tube blank is pressurized to 0.1-5 MPa;

then cooling to below 600 ℃, opening an air-expanding die, and taking out the formed double-covered edge composite part;

2. The helicopter blade edging forming method of claim 1, wherein the thin-walled titanium alloy tubing has a wall thickness of between 0.1mm and 3.0 mm.

3. The helicopter blade hemming forming method of claim 1 wherein the inflatable mold includes a left mold, a right mold, a front stop and a rear stop; the opposite sides of the left die and the right die are respectively provided with a die groove, and the die groove structure corresponds to the edge-covering part structure; the front stop block and the rear stop block are identical in structure and are symmetrically arranged; the front stop block is provided with a second through hole.

4. A helicopter blade edging forming method according to claim 3, characterized in that said installing the tube blank in an inflatable mould comprises:

5. The helicopter blade taping forming method of claim 1, wherein the cutting the double taping composite part includes: and cutting the double-edge-covered composite part in a laser cutting mode according to the shape digital-analog of the edge-covered part.